Mound

The largest artificial mound in Europe is Silbury Hill, near
Avebury (Wiltshire). It covers 5 acres, 34 perches, and measures at the
base 2,027 feet; its diameter at top is 120 feet; its slope is 316
feet; perpendicular height, 107 feet; and it is altogether one of the
most stupendous monuments of human labour in the world.

Alyattes, in Asia Minor, described by Herodotus, is somewhat larger
than Silbury Hill.